<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script>
			function run() {
				alert("hello world");
			}
			var t = setTimeout(run,5000); //页面运行5秒后出现
			
			// clearTimeout(t); // 取消一次性定时器
		</script>
	</head>
	<body>
	</body>
</html>
